Press-fit assembly devices are known in the art, and have been used to press one component into another to assemble the components together into a product. To get a good fit between the components, that is, a fit that meets anticipated loading, a minimum pressure must generally be applied to the components being assembled; otherwise, the components could come apart or otherwise fail in use. Thus, it has been desirable to monitor the pressure applied during assembly to ensure that the product meets design criteria.
Press-fit equipment is frequently used in assembling load-bearing products such as roller chain. Roller chain is assembled by pressing bushings into the pitch holes of roller linkplates and pressing pins into the pitch holes of pin link plates. The basic integrity of the chain relies on the control of these press fits. Too little force in the press fit operation can result in premature failure of the chain. Too much force in the press fit operation can damage chain components and can damage the tooling used to assembly the chain.
In assembling products such as roller chain, hydraulic press equipment could be used, allowing for a constant or periodic monitoring of the pressures used in assembling the parts being produced. However, mechanical press equipment is generally more productive, producing a greater number of parts per unit of time. In addition, in an assembly line with multiple press-fit devices arranged for serial operations, it is frequently critical that the timing of each press station be coordinated with the operation of the adjacent station or stations. While mechanical presses can be readily tied together to keep them in phase, it poses more of a problem to maintain a group of hydraulic presses in phase.
While mechanical presses may be more efficient than hydraulic ones, determining whether sufficient pressure was applied by the mechanical press for producing a strong fit is problematic. In addition, care must also generally be taken to assure that the pressure applied is not so great as to damage the components. Moreover, if the components and press pieces are not properly aligned, an excessive pressure may be developed that could damage the press equipment.